Hello, Welcome to Just Answer and thanks for your question. It really isn't possible to say what is causing the increase in pressure without knowing your complete medical history and doing some extensive tests, which we can't do online. Pressure within the eye itself is often due to glaucoma and that is treated with medication, or perhaps eye surgery to relieve pressure on the optic nerve(s).
Overweight can put a huge strain on the circulatory system. Excess weight causes heavier demands on the heart and blood vessels to circulate blood. This can cause fluid to leak from the blood and collect in places it should not. It is most often seen in the lower extremities, but can also be seen in other parts of the body, including the lungs, etc.
There is also a possibility that you have some minor form of defect in the normal drainage of excess brain and spinal fluid. It must be minor or you would be having this problem constantly and they would have operated years ago to install a shunt from the brain to the abdomen.
I'm sorry that all we can offer is some general information, since we really don't have the whole picture of what is going on.
Thank you for your answer.
I also have left ventricular hypertrophy (thickening of the heart muscle). Could this also explain your answer in para 2. Does exercising make the heart over work and cause the fluid to leak from blood?
Ventricular hypertrophy is sometimes caused by being overweight, since it forces the heart muscle to work harder and enlarge.
Some athletes will have larger hearts from heavy exercise, and in them it is not a concern. Someone who has ventricular hypertrophy from overweight should not avoid exercise, since this improves weight loss, but they shouldn't go headlong into an ambitious exercise program without a consult with their physician either. Most people need about 30-60 minutes of healthy exercise every day. That can something like brisk walking. Those who are not accustomed to that much activity should begin slowly, 5 minutes at a time, after a consult with their physician.